Glaucoma, What is it?

Article from The Second Wind

Dear Dr. Weaver,

A few of my friends have mentioned to me that they were recently diagnosed with chronic open angle glaucoma. I haven’t had an eye exam in years. So, I was wondering how I can tell that I’m developing glaucoma.

Sincerely,
Edith

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Dear Edith,

Chronic open angle glaucoma is an insidious disease that damages the optic nerve over a period of time. The optic nerve contains millions of nerve fibers leading from the retina to the brain. Damage to the optic nerve from glaucoma affects these nerve fibers, which thereby affects a person’s vision. The nerve fibers responsible for a person’s peripheral vision are lost first. Since people are not usually susceptible to vision changes in their peripheral visual field, the loss of these nerve fibers go unnoticed. Eventually, prolonged damage to the optic nerve causes more and more of the retinal nerve fibers to lose function. When the disease is quite advanced, glaucoma will start damaging the nerve fibers responsible for a person’s central vision. This is when aggressive treatment must be initiated as soon as possible, because any vision that is lost is not recoverable.

When you go in for an eye examination, the eye doctor is looking for a multitude of risk factors that would indicate that you have glaucoma or are a suspect of developing glaucoma. Some of these risk factors are a high intraocular pressure and cupping (loss of nerve fibers) of the optic nerve. Other risk factors are increased age and a family history of glaucoma.

To gain more information about a person’s risk of developing glaucoma, the eye doctor will usually order a battery of tests. These typically include a peripheral visual field test, a photo or computerized scan of the optic nerve, a scan of the nerve fibers in the retina, and an ultrasound of the cornea to determine its thickness. After interpreting all of this information, the doctor will then determine if treatment is necessary.

The only risk factor that the doctor can directly control is the intraocular pressure. The goal is to lower the pressure inside the eye to a level that the doctor believes will reduce or halt damage to the optic nerve, to preserve as much remaining vision as possible. What may be a high pressure for one person may be entirely normal for someone else. Everyone is different, so the treatment also differs.

The pressure inside the eye can be thought of as water in a kitchen sink. Controlling the amount of fluid (water level) in the eye is the inflow (faucet) and the outflow (drain). When the intraocular pressure increases, this occurs by too much water coming into the sink, something clogging the drain, or a combination of both. This eye pressure can be reduced with prescription eyedrops that act on both the inflow and outflow mechanisms to lower the eye pressure. However, patient compliance with using eyedrop medication daily can be an issue, especially since the patient usually has no symptoms in early glaucoma. Poor control results in a higher intraocular pressure, allowing glaucoma to progress. If the pressure is not controlled well, your eye doctor may also recommend a non-invasive procedure involving laser treatment to increase the outflow to lower the intraocular pressure. It is possible that a person may still require eyedrops after laser treatment, depending on how well the intraocular pressure was lowered.

Glaucoma is one disease out of a multitude of eye conditions that exhibit symptoms only when it is very advanced and severe. Individuals diagnosed with glaucoma and treated appropriately can live their entire life without any noticeable vision loss. It is extremely important to seek an eye exam yearly so that your eye doctor may ensure that your eyes are healthy, or to establish a treatment regimen to preserve the vision that you have.